1. Field
Aspects of embodiments of the present invention relate to an organic light emitting display device and a driving method of the organic light emitting display device.
2. Description of the Related Art
Recently, various flat panel displays having reduced weight and volume when compared to that of cathode ray tube devices have been developed. Example flat panel displays include a liquid crystal display, a field emission display, a plasma display panel, an organic light emitting display device, and the like.
Among the flat panel displays, the organic light emitting display device, which displays an image using organic light emitting diodes (OLEDs) that generate light by recombination between electrons and holes, has a rapid response speed and is driven with low power consumption. The organic light emitting display device includes a plurality of data lines, scan lines, and a plurality of pixels arranged in a matrix form at crossing regions of the data lines and scan lines, and between power lines. The pixels each generally include an OLED and at least two transistors including at least one driving transistor.
The organic light emitting display device has low power consumption. However, an amount of current flowing to the OLEDs varies according to a variation in threshold voltage between driving transistors included in each of the pixels, which generates a non-uniform display. For example, the driving transistor characteristics may vary according to a variable in a manufacturing process of the driving transistor provided in each of the pixels. Presently, it is impossible or impractical to manufacture all of the transistors of the organic light emitting display device to have the same characteristics. Therefore, a variation in threshold voltage of the driving transistors occurs.
One proposal to address this is to add a compensation circuit including a plurality of transistors and a capacitor to each of the pixels. The compensation circuit compensates for the variation in threshold voltage of the driving transistors by diode-connecting the driving transistor during a scan signal supply period.
Meanwhile, other proposals to improve image quality include driving a panel at a high resolution and/or a high driving frequency. However, when the panel is driven at a high resolution and/or high driving frequency, the threshold voltage may not be adequately compensated for in areas of low brightness, such that low brightness mura (unevenness or nonuniformity) is generated. For example, when displaying a low brightness image, a relatively small amount of current flows to the pixels, such that the threshold voltage may not be adequately compensated for during a set time (for instance, a predetermined time, such as during a scan signal supply period).